Chapter 34, Problem 33A

Summary Introduction

To write:

About why nephrons unable to remove proteins

Introduction:

The excretory system is the system of an organism's body that performs the function of excretion, the bodily process of discharging wastes. Several parts of the body are involved in this process, such as sweat glands, the liver, the lungs and the kidney system. The kidneys maintain homeostasis by removing wastes and excess water from the body and by maintaining the pH of the blood. The kidneys are the major excretory organ in the body. It is a bean-shaped organ that is involved in urine formation performs filtration of blood.

Answer to Problem 33A

Correct answer:

The correct answer is option (B) proteins cannot be filtered.

Explanation of Solution

Explanation/justification for the correct answer:

Option (B) proteins cannot be filtered. Proteins are too big to fit through the capillary walls, so they remain in the bloodstream and cannot be filtered. If the kidneys work properly, the nephrons never remove the protein that is why they aren't found in a healthy person's urine. So, the correct answer is option (B).

Explanation for incorrect answer:

Option (A) collecting ducts are too small. No, it is not too small. It is the last portion of the nephron which participates through reabsorption and excretion in the electrolyte and fluid balances. Proteins do not reach the urine because of their larger size. So, this is an incorrect option.

Option (C) proteins never enter the nephron. No, proteins do not enter the nephron. They remain in the bloodstream. So, this is an incorrect answer.

Option (D) proteins are reabsorbed by nephrons. Because of large size, proteins do not enter the nephron. They remain in the bloodstream. Therefore, they are not reabsorbed by nephrons. So, this is an incorrect answer.